When and Why to Test Your Vaginal Microbiome

The vaginal microbiome is a complex and essential ecosystem of bacteria and fungi that lives inside the vagina. And while many of us grew up thinking all bacteria are bad, the reality is that beneficial bacteria—especially Lactobacillus—play a critical role in maintaining vaginal and reproductive health.

Dr. Krystal Thomas-White, Senior Scientist at Evvy and microbiologist specializing in the vaginal microbiome, shares her insights on why testing your vaginal microbiome matters—especially when you're trying to conceive, navigating recurrent infections, or experiencing hormonal shifts like menopause.

What is the vaginal microbiome?

"We are walking, talking ecosystems, and whole worlds live and die in us every day."

That’s how Dr. Thomas-White describes the microscopic world inside the vagina. Humans are the only species with a Lactobacillus-dominant vaginal microbiome—bacteria that help keep pH low, fend off pathogens, and support immune health.

Thanks to research at Evvy, scientists can now identify a wide variety of bacteria and fungi in the vaginal microbiome using metagenomic sequencing. This gives us a clearer picture of what’s going on inside our bodies and how it may be contributing to recurring symptoms or imbalances.

The vaginal microbiome and fertility

One of the most promising areas of vaginal microbiome research is its connection to fertility.

The vaginal microbiome is part of our immune system and can help modulate inflammation—an important factor in conception and pregnancy. A Lactobacillus-dominant vaginal microbiome is associated with better IVF outcomes, lower risk of preterm birth, and overall reproductive health.

Evvy’s new Fertility Insights analyze these patterns by scoring the presence of protective bacteria like Lactobacillus crispatus, microbiome diversity, and levels of fertility disruptors such as Gardnerella and Prevotella.

Even sperm are equipped with sensors to detect bacteria, which suggests an evolutionary link between the vaginal microbiome and successful reproduction—even if we don’t fully understand how that works yet.

Should you test your microbiome when trying to conceive?

Dr. Thomas-White compares vaginal microbiome testing to doing a 23andMe panel before pregnancy: “It’s information you may want to know as you’re preparing for the fertility journey.” With very little downside and growing research into its relevance, many people use it to better understand their chances of conception.
This is especially important given that one-third of infertility cases are considered “unexplained.” Evvy’s Fertility Insights aim to change that by helping uncover potential microbial causes of inflammation or imbalance that may otherwise go undetected.

Estrogen’s role in vaginal health

Estrogen and Lactobacillus are closely linked. Estrogen increases glycogen in the vaginal lining—essentially food for Lactobacillus—which allows protective bacteria to thrive.

When estrogen levels fall, such as during menopause or postpartum, glycogen decreases. This can lead to fewer Lactobacilli, thinning of the vaginal wall, dryness, discomfort, and increased risk of infection.

Topical estrogen has been shown to restore microbial balance by replenishing glycogen stores—without raising systemic estrogen levels—making it a helpful tool for menopausal symptoms and UTIs.

When is it helpful to test your vaginal microbiome?

While there’s no one “right” time to test, microbiome testing can be particularly helpful if:

• You’re experiencing recurrent or unexplained infections
• You want to understand how your microbiome shifts with your cycle, stress, or antibiotic use
• You’re preparing for fertility treatments or trying to conceive
  
  

Testing with Evvy provides a snapshot of your current vaginal ecosystem, and repeated testing over time can help identify patterns, changes, and effective interventions.

What happens after you get your results?

Every Evvy test is reviewed by a physician who guides you through your results and options. Next steps might include:

• Targeted antibiotic treatment, based on your exact bacterial makeup
• Probiotic support to help rebalance your microbiome
• Lifestyle recommendations, like managing stress or using barrier protection

Do probiotics actually work?

Probiotics can be a valuable tool—especially after antibiotic use—but there’s a catch: the strains currently available don’t usually colonize the vaginal microbiome. Still, they can act as a “placeholder,” occupying space so harmful bacteria don’t repopulate.

Research is underway to develop strains that do colonize effectively, and to better understand why probiotics work well for some but not for others. Your starting microbiome, stress levels, and even delivery method all play a role.

Are standard BV tests enough?

Often, no. Many gynecologists diagnose bacterial vaginosis (BV) based on symptoms alone. If testing is done, it’s typically limited and doesn’t identify the full range of bacteria or fungi that may be present.

Evvy’s metagenomic test, on the other hand, offers a comprehensive view—making treatment more targeted and effective.

What do we know about vaginal fungi?

Fungal research is far behind bacterial research. The vaginal mycobiome—the fungal counterpart to the microbiome—is poorly studied, but we know Candida is the main culprit in yeast infections. Interestingly, many people have Candida without symptoms, and we don’t yet understand why.

This knowledge gap is a clear example of how gender disparities in medical research are still playing out.

Can probiotics be personalized?

Yes—and Evvy is one of the few places offering custom solutions. In addition to oral options, Evvy offers vaginal suppository probiotics, which are hard to find elsewhere. These formulations use well-researched strains, compounded at high quality.

Still, individual results vary. What works for one person may not work for another, and researchers are still uncovering why.

What’s next in vaginal microbiome science?

Dr. Thomas-White sees a future where vaginal health follows the same path as cancer research did in the early 2000s: moving from one-size-fits-all labels to subtype-specific diagnoses and treatments.

“Right now, we talk about BV as if it’s one condition,” she says. “But there are many distinct subtypes. Once we can diagnose them properly, we can create treatments that actually work.”

Evvy is building that future—powered by real-world data and driven by the people who test with them.

Curious what your microbiome says about you?

Whether you're dealing with recurring symptoms, unsure if it’s yeast or BV, navigating perimenopause, or preparing to grow your family—your vaginal microbiome holds critical answers. Evvy’s at-home test gives you a clear, science-backed window into what's going on in your vaginal microbiome, why it matters, and what you can do about it. Now, with Fertility Insights included, you’ll also get personalized data on your microbiome and how it relates to fertility outcomes—so you can take control of your health, no matter where you are in your journey.